Doha College hands down. It's more established, non-profit, better resourced, and has the sponsorship of the British Embassy for the secondary school.

If your children are in primary school, Doha College is a good option, but by general consensus DESS is the best (even more established, is solely for primary, and has the sponsorship of the British Embassy).

Doha British is acceptable, but, ultimately like so many other schools, it is less well established and is a business, which means that profitability for the owners is important; unlike DC and DESS, who have all the tuition and fees going back into the school.